Patent Literature 1 describes a polishing brush in which a grinding element bundle formed with a plurality of wire-shaped grinding elements protrudes from the end surface in the direction of the axis of center of rotation or protrudes from the outer peripheral surface of the grinding element holder. Each of the wire-shaped grinding elements in this literature is formed by impregnating and hardening an assembly of alumina fibers, silicon carbide fibers, carbon fibers, silicon nitride fibers or glass fibers with binder resin. The wire-shaped grinding element composed of inorganic filaments has high hardness and thus has high grinding/polishing capability.